A detailed study is being made of the lipid and fatty acid composition and metabolism in reproductive tissue of male animals. The biosynthesis and interconversion of fatty acids is being studied in tests of animals, particularly, the rat in vivo and in vitro. Changes brought about in these metabolic processes by age, diet, pathological conditions and hormonal influences are being determined. Findings in the studies of lipid composition and metabolism are supplemented with histological studies of the tissue.